Electric discharge device



b 1931 A. M. SKELLE TT v ELECTRIC DISCHARGE DEVICE Filed March 25, 1927' IINVENTOR $iESz Patented Sept, 13, 1932 I "man u. snnm'r' i;

I ST. LbUIS, MISSOURI, ASSIGNOB '10 WESTINGHOUSE ELECTRIC a manurao'rfiafiw comm, a coaroaa'rron or rmmsnvama m-.ncrnrc mscnanen nnvron Application fled Iarch as, 19:7. Serial in. 178,870.

My invention relates to electric discharge devices, and more particularly to such devices when utilizedin frequency-responsive relay circuits. "f One object of my invention is to provide a combination of electric discharge devices that 'is selectively responsive to a definite frequency.* J

Another object of my invention is to pro- 19 vide a frequency-responsive relay system utilizingelectric discharge devices that consume no power in the intervals'between their activation by a predetermined frequency. Another object of my invention is to provide a. frequency-responsive relay system capable of handling a comparatively large amount of power. f

Another object of my invention is to provide a frequency-responsive system particularly adapted to be used in connection with the remote control of relatively large apparatus. t r l A still further object of. my invention is to provide a frequency-responsive electric discharge device particularly adapted for use 'in systems of the typedescri'bed.

There has arisen, in connection with remote-control systems of various kinds, the need for an inexpensive frequency-responsive into two main classes, those responsive to radio frequencies, and those responsive to audio frequencies. Relays of the latter type usually {comprise a tuned circuit arranged to control a mechanical member that has a; period of oscillation equal to the period to-which the responsive circuit is tuned, For frequencies within the audio range, such relays have given a fair degree of satisfaction, but, when 4 the controllingfrequency lies in the radio, or super-audible range, it is a difiicult matter to provide a mechanically tuned member that is sufliciently sensitive.

By the present invention, I have succeeded in entirely dispensing with mechanicallytuned Inembers,-and utiliz e', instead, the property which is possessed by rarefied gas of ionizing and conducting current upon the ap plication of an appropriate voltage, across electrodes incontact therewith. The ionizarelay. Such'relays are, in general, divided tion of the path between the electrodes, upon the application of the desired frequency, estabhsh'esa id-leak path for an electric dischar e device, preferably of the type disclosed and claimed in a copending applicationTof D. D. Knowles, Serial No. 149,290, filed'November 19, 1926. v

The electric discharge device, in turn, may control a relay of any suitable directly, actuate an appropriate indicating or mechanism-controlling system.

Among the features that I consider characteristic of my invention, are those set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, to-' e or may gether with further objects and advanta es thereof, will best be understood by re erence to the following description, taken in connection with the. accompanying drawing:

Thesingle figure of the drawing is a diagrammatic view of a preferred embodiment of my invention, in which the electric discharge devices are illustrated partly in section and partly in elevation;

Referring specifically to the drawing, an electric discharge device '1, comprising an envelope 2, in which arepositioned a. plurality of cold electrodes 3, 4 and 5,. is provided with a tuned input circuit comprising an inductor 6 and a condenser 7, the circuit being conductively connected between the electrodes 3 and 5. Bycharacterizingthe electrodes ofthe tube 1 as co'ld,\it is my intention to thereby distinguish between my control-device and discharge devices of the type requiring an external power source for rendering the cathode thereof thermionically active. The envelope preferably contains neon or argon at a pressure of 1000 microns, andthe space between the electrode 3 and the electrode 4: is so chosen that it is less than the mean free path of the gas'molecules.

A tunable circuit,- compris'in an inductor 8 and a condenser 11, is couple to the input circuit of the discharge device 1, and isarranged to be energized from a source 12 of 1 alternating potential. \Ihe source 12 is illustrated as an alternating-current generator,

but it is within the scope ofdny invention to utilize carrier currents, either wire or radio,

or any desired modulation thereof, for the actuation of my device.

A second electric discharge device 13 of the type disclosed in the Knowles application referred to, comprises an envelope 14 in which are positioned a cathode 15, an

anode 16, and a grid element 17. The grid element 17 is connected to the electrode 4 of the discharge device 1 by a conductor 18, and

the cathode 15 may be connected to the electrode 5 by a conductor 21, if desirable. The latter connection may be omitted without materially interfering with the operation of 15 my invention, and, for that reason, 'ithasbeen indicated by a dotted line.

A relay winding 22, in series with the secondary 23 of a transformer 24, is connected between the anode 16 and the cathode 15 of 20 the discharge device 13, the primary winding of the transformer being arranged to be energized from a source 26 of alternating current. A movable contact 27 and a fixed contact 28 are associated with the rela winding 22 and are arranged in circuit wit a source of potential 31 and an indicating device 32. p It is entirely possible to dispense with the relay and the associated contacts, and to actuate suitable mechanisms directly by the output current of the electric discharge device 13. This modification being believed obvious, it has not been illustrated.

In the operation of my invention, the input circuit comprising the inductor 6 and the condenser 7, is tuned to the frequency which it is intended to receive. The circuit comprising the inductor 8 and the condenser 11 may also be tuned, if desirable, although this is not absolutely necessary. The source 12 of alternating current, as has been previously pointed out, may be either an alternatin current generator, or may be the output circuit of receiving apparatus associated with either an antenna or with line wires. The origin of the alternating frequency is immaterial.

As is well known to those skilled in the art, 'maximum potentials will be established across a resonant circuit when it is subjectedto voltages at the frequency to which it is tuned. I take advantage of this fact byv so spacing the electrodes 3 and 5 that a potential established across them by an incoming signal at the frequency to which the circuit 67 is tuned is suflicient to ionize the gas therebetween.

As explained in the copending application of Knowles, previously referred to, the grid member 17 tends to accumulate a high negative charge when an alternating potential is applied between the cathode 15 and the anode 16. Such an alternating potential is conveniently applied through the' transformer 25 from the source 26. The high negative charge acquired by the grid member is sulfi- 35 cient to block the electric discharge device 13 and prevent ionization of the gas between the anode 16 and the cathode 15.

- By reason of the connection between the grid member 17'and the electrode 4, the electrons accumulated by the grid member are afforded a leakage path upon ionization of the gas in the electric discharge device 1. Consequently, when a si nal is received at the frequency to which the tuned input circuit is adjusted the negative charge upon the grid member 17 at once leaks away, permit-- ting the plotential applied between the anode 16 and t e cathode 15 to cause a glow discharge therebetween. As explained in the Knowles application, the discharge. in the grid controlled device is substantially unidirectional, and it may, accordingly, be utilized to actuate either the relay 22 or to energize a solenoid which controls the operation of suitable mechanisms.

Inasmuch as the distance between the electrode 3 and the electrode 4 is less than the mean free path of the gas molecules, the high negative charge accumulated by the electrode 4 is prevented from leaking until such 99 time as initial ionization of the as is accomplished under the influence of t e frequency to which the input circuit is tuned. It is thus apparent that, even though an alternating potential be continually applied between the anode 16 and the cathode 15, no current will flow in the device 13, and the relay will not be actuated unless there is an incoming signal of the same frequency as that of the tuned circuit.

It is to be noted that the tube 13 is potentially operated, as distinguished from current operated. By a potentially 0 erated device, I mean a device that respon s to the ef-- fect of extremely minute currents, the response being produced by the electrical action of potential differences impressed in the device by the flow of the small currents. Thus, an electroma etic relay is current operated as distinguis ed from a device such as the tube 13 which is potentially operated.

It is also within the scope of my invention to utilize the ionization of the inter-electrode path in order to supplement, or alter, the resistance of a grid-leak resistor associated with a three-electrodethermionic amplifying device of the usual and wellknown type.

As is familiar to those skilled in the art, the alteration of the grid potential occasioned by a change in the grid leak may be caused to control the plate, or output, current, and to, thus influence the action ofa sensitive re ay. 1

It is accordingly apparent that I have, by my invention, provided a frequency-selec- 125 tive relay system which is extremely critical in operation. By reducing the losses in the tuned circuit to the minimum, thus increasing the sharpness of tuning, the selectivity of my system may be greatly'increased.

Conversely, when it is desired that the relay shall function for frequencies in the neighborhood of a given frequency, it is merely necessary to interpose a definite amount of positive resistance in the tuned circuit in order to broaden thetuning thereof.

a remote generating station, it may be utilized for the turning on or oil' of street lighting systems, or for the remote control of devices, such as torpedoes or aeroplanes, designed to be manipulated from a distance.

Numerous other uses for my system will obviously be apparent to those skilled in the art, as well asmany modifications thereof. My invention, therefore, is not to be, limited except insofar as is necessitated by the 'prior art and as indicated by the appended claims.

I claim as my invention:

1. In combination, a tube having a'lowpressure gas therein, a plurality of cold electrodes mounted within said tube, the distance between certain of said electrodes being less than the mean free path of the gas molecules, means for applying a potential across cer tain of said electrodes in order to ionize the space between the first mentioned electrodes, and means whereby the change in resistance between said first mentioned electrodes permits the actuation of a potentially-controlled relay system. i I

2. In a frequency-responsive system, a body of ionizable gas, a plurality of cold electrodes mounted therein, means, including a tunable circuit, for establishing an ionizing potential between certain of said electrodes, a second body of ionizable gas having a plurality of cold electrodes including a grid member mounted therein, and means whereby the ionization of-said first mentioned body of gas is utilized to permit 1t)he leakage of electrons from said grid mem- 3. In combination, an electric discharge device comprising a body of ionizable gas and a plurality of cold electrodes therein, certain of said electrodes being spaced apart a distance greater than the mean free path of the gas molecules and the distance between one of said last-named electrodes and one of the remaining electrodes being less than the mean free path of the gas molecules, and an oscillatory circuitconnected across said widely spaced electrodes, whereby the gas between said widely spaced electrodes may be so ionized by potentials developed across said oscillatory circuit as to permit the path between the closely spa "ed electrodes to become conducting. I

4. In combination, an electric discharge device comprising a body of ionizable gas and a plurality of cold electrodes therein, certain of said electrodes being spaced apart a distance greater than the mean free path of the gas molecules and the distance between one of the remaining electrodes and one of said spacedapart electrodes being less than the mean free path of the molecules, an electric discharge device having a control-electrode, a connection between said control-electrode and one of said closely spaced electrodes, and means for ionizing the gas between said spaced apart electrodes to thereby render the gas between said closely spaced electrodes sufficiently conductive to change the chargeretaining ability of said control-electrode.

5. A gaseous valve comprising a plurality of conductors, one of said conductors being separated from one of said other conductors by a distance less than the mean-free-path of the gas contained in said valve, means for impressing an electric charge on said first named conductor, and ionization means for providing a conducting path between said first named conductor and said last named conductor, whereby the charge on said first named conductor is neutralized.

6. A gaseous valve comprising a pair of conductors separated by a distance less than the mean-free-path of the gas contained in said valve and a pair of conductors separated by a distance greater than the mean-free-path of the gas contained in said valve, and means for impressing an ionizing potential between said last named conductors.

In testimony whereof, I have hereunto subscribed my name this l8th day of March,

ALBERT M. SKELLETT. 

